Polymer materials excellent in low hygroscopic property, transparency and heat resistance are required in the technical field of plastic optical members, and as one of polymer materials capable of satisfying those, a fumaric acid dialkyl ester polymer is known (for example, JP-A-62-169807 and J. Macromol. Sci., A25 (5-7), 537-554 (1988)). Fumaric acid dialkyl ester is a rare monomer that radically polymerizes, even though it is 1, 2 disubstituted ethylene, and a polymer obtained therefrom has extremely high heat resistance. However, there was the disadvantage that its homopolymer is a polymer that steric hindrance is too high, so that it is difficult to increase a molecular weight (at most about 100,000), and further, it is rigid and is liable to be a rod-shape, so that mechanical strength (for example, tensile strength) is weak, resulting in a brittle polymer.
To improve this disadvantage, a copolymer with an alkyl vinyl ether is proposed (JP-A-2000-143741). However, mechanical strength of the copolymer is not sufficient. Further, an example of a copolymer of a fumaric acid dialkyl ester with a monomer such as styrene or acrylonitrile is reported (Journal of Polymer Science: Part A: Vol. 30, 1559 (1992)), but mechanical strength, hygroscopic property and the like are not referred to.
On the other hand, an antireflective film generally prevents contrast from decreasing due to reflection of outside light or prevents an image from reflecting, in displays such as cathode ray tube displays (CRT), plasma displays (PDP), electroluminescence displays (ELD) and liquid crystal displays (LCD), and therefore is provided on the outermost surface of displays in order to reduce reflectivity using principle of optical interference.
Such an antireflective film can generally be produced by forming a low reflective index layer having an appropriate thickness and having a refractive index lower than that of a support on the support. To realize a low refractive index, a material having a refractive index as low as possible is desired for the low refractive index layer. Further, the antireflective film is required to have high mar resistance in order to use the same on the outermost surface of a display. For example, in a thin film of about 100 nm, in order to realize high mar resistance, strength of a coating film itself and adhesion to a lower layer are required.
To decrease refractive index of a material, means of (1) introducing fluorine atoms, and (2) decreasing density (introducing voids) are known. However, either of those means have the tendency that coating film strength or adhesion at interface decreases, resulting in deterioration of mar resistance, and low refractive index and high mar resistance were not achieved in combination.
As a method of increasing coating film strength, there is a method of using a fluorine-containing sol gel film as described in JP-A-2002-265866 and JP-A-2002-317152. In this method, however, there are great restrictions that (1) long-term heating is required for curing, and load of production is large; (2) there is no resistance to saponification liquid (alkali treatment liquid), and in the case of saponification treating a plastic film surface, the treatment cannot be carried out after film formation of an antireflective film; and the like.
On the other hand, JP-A-11-189621, JP-A-11-228631 and JP-A-2000-313709 describe means of improving mar resistance by introducing a polysiloxane structure in a fluorine-containing copolymer to decrease a friction coefficient of coating film surface. This means is effective to improvement of mar resistance to a certain extent, but sufficient mar resistance is not obtained for coating films lacking in substantial coating film strength and interfacial adhesion.
Further, WO 2004-017105 pamphlet describes means of improving mar resistance by using a fluorine-containing copolymer and inorganic fine particles in combination to improve coating film strength and interfacial adhesion. In this means, however, it was found that there is the case that inorganic fine particles are not sufficiently dispersed in a matrix of the fluorine-containing copolymer, crude density of inorganic fine particles causes in the coating film, and haze rises. This problem is particularly problematic in a smooth surface low reflective film having no antiglare property.
Further, plastic optical members have the advantage that production and processing are easy, and other advantages, as compared with quartz-based optical members having the same structure, and various applications such as optical waveguides are recently attempted. In particular, plastic optical fibers (POF) have the disadvantage that because element wires are all constituted of a plastic, transmission loss is relatively large as compared with quartz types, but have the advantages that they have good flexibility, are lightweight, have good processability, and are easily produced as fibers having large bore diameter as compared with quartz-based optical fibers.
As materials for optical fibers, polymethyl methacrylate (PMMA) that is inexpensive and is easily processed is widely used. However, because of a polymer having high water absorbing property, the polymer has poor moisture resistance and can only be used in the limited uses. As means to improve moisture resistance, it is an effective means to introduce fluorine atoms. However, it is difficult to establish high glass transition temperature (Tg), that is, heat resistance, in combination with the moisture resistance. For example, poly(2,2,2-trifluoroethyl methacrylate) in which methyl groups in side chains of PMMA are merely changed fluorine-containing alkyl groups decreases Tg, and POF using this has very poor heat resistance. One of means to solve this problem is all fluorine polymer (TEFLON, registered trademark, AF amorphous fluoropolymer, John Scheires, 1997, Modern Fluoropolymers, p 397-398, John Willwy & Sons Ltd.), and this is an excellent material satisfying various performances such as heat resistance, low hygroscopic property, low transmission loss and the like. However, synthesis of a perfluorinated (diene) monomer that is a raw material of this polymer is very complicated, and there is the problem that cost of a polymer is high.